Dispensing liquid, and gas and powder products from a vessel under pressure provides a much greater force behind the dispensed spray stream than that achieved with the alternative spray pump. A drawback with pressurised aerosols is that the high spraying force in the cans is a result of using highly compressible hydrocarbons. It is well established that hydrocarbons are deleterious to the environment affecting the ozone layer and atmosphere in general. Furthermore, hydrocarbons are highly combustible and therefore dangerous if not used or disposed of thoughtfully.
A further drawback with pressurised cans and other vessels is that the can is pressurised once, only at filling, and hence provides the greatest dispensing pressure when the can is full but as the contents are reduced, and the pressure differential between the can interior and can exterior at atmospheric pressure is also reduced, the force behind the spray stream becomes weak. Difficulties are experienced with expelling low amounts of product remaining in the vessel.
Attempts have been made to maintain the interior of the vessel in a state of relatively constant pressure, that is over a constant non-decreasing pressure range, by providing a pressure regulating unit inside the vessel. The regulating unit is generally pressurised with the same gas with which the vessel is pressurised. These units are designed to release stored quantities of pressurised gas into the can interior as the can contents are dispensed from the can, thereby maintaining the pressure level inside the vessel for much longer. These known units are generally small in size comprising precisely manufactured components necessary to interact accurately.
Consequently, the pressure regulating units are often either improperly constructed failing frequently, or are too expensive to manufacture and unable to compete in price with regular aerosols or spray cans.
The main solution sought with the present invention is to provide a pressure regulating device that operates effectively in regulating pressure within a pressurised vessel but is also manufactured economically for producing a market competitive product.